Life After Higgs: What's Next for World's Largest Atom Smasher?

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Less than five years after it went live, the Large Hadron
Collider has confirmed the existence of a Higgs boson, the
particle which may explain how other particles get their mass.

The confirmation comes today (March 14), after a July 2012
announcement of the elementary particle's discovery. At the time,
researchers strongly suspected they'd
found a Higgs, but needed to collect more data. Since then,
they've more than doubled the amount of data they have on the
particle using the Large Hadron Collider (LHC), a 17-mille-long
(27 kilometers) underground ring on the French-Swiss border where
protons zing around at near the speed of light.

With a Higgs boson discovered, what more is there for this
enormous and unusual piece of machinery to do? Lots, according to
physicists.

For one thing, scientists are still working out whether the
Higgs boson they've discovered fits the Standard Model of
physics or if it better fits another theory. (So far, the
Standard Model appears to be the winning candidate.)

And the hunt for the Higgs boson is just one of the ongoing
projects at the particle accelerator. Other projects have such
humble goals as explaining dark matter, revealing the symmetries
of the universe and even looking for new dimensions of space,
according to the U.S. Department of Energy and the National
Science Foundation. [ 5
Reasons We May Live in a Multiverse ]

"It really is a machine that's capable of going to higher
energies, maybe ultimately to a factor of seven times higher
energy," said Peter Woit, a physicist at Columbia University.
"Which means going to distances seven times smaller and basically
looking for anything you can find."

ALICE (A Large Ion Collider Experiment @ CERN):
By smashing particles together, scientists can recreate the first
few milliseconds after the Big Bang, illuminating the early
history of the universe. A detector 52 feet (16 meters) high and
85 feet (261 m) long enables scientists to study what's known as
quark-gluon plasma. The researchers collide heavy ions,
liberating their quarks and gluons (quarks are the constituent
part of protons, which are held together by gluons). It takes a
machine like the LHC to separate these atomic particles and study
them individually.

ATLAS (A Toroidal LHC Apparatus): This is the
experiment that observed a Higgs in July. But ATLAS's work isn't
done. The LHC, and the ATLAS detector, are currently in shutdown
mode, preparing for an energy increase. When LHC starts up again
after 2013, the atom smasher will be able to fling protons at
each other at 14 teraelectronvolts (TeV), double its previous 7
TeV.

ATLAS has a broad mission. It's a tool that can search for extra
dimensions of space and supersymmetry, the idea that every known
particle has a "superpartner particle," an important component of
string theory. Supersymmetry would, in turn, help elucidate dark
energy, which may exist in the vacuum of space and be responsible
for the acceleration of the universe's expansion. ATLAS is also
part of the
search for dark matter, a mysterious form of matter that may
make up more than 95 percent of the universe's total matter
density, but which is virtually unknown. [ Whoa!
The Coolest Little Particles in Nature ]

CMS (Compact Muon Solenoid): Like ATLAS, CMS is
a jack-of-all trades. The detector is meant to explore the same
questions about the origins of the universe and the fundamentals
of matter.

LHCb (Large Hadron Collider beauty): The LHCb
project studies how B mesons decay. Mesons are particles made of
a quark and an antiquark bound together; a B meson contains a
flavor of quark known as the "b-quark." Studying this decay helps
scientists understand imbalances between
antimatter and matter. During the Big Bang, matter and
antimatter should have been created in equal amounts, leading
physics theories suggest. Even so, the world is made up nearly
entirely of matter, so the mystery remains: What happened to the
antimatter?

The LHCb will also study the decay products of the Higgs boson
particle.

LHCf (Large Hadron Collider forward): This
project is just spacey. The LHCf is focused on the physics of
cosmic rays, charged particles that flow through space.
Ultra-high-energy
cosmic rays remain a mystery to physicists, who hope to find
out their origins with the help of the LHCf experiment, which is
a joint collaboration with the Pierre Auger Observatory in
Argentina and the Telescope Array in Utah.

TOTEM (Total Cross Section, Elastic Scattering and
Diffraction Dissociation): The TOTEM detector is small
by LHC standards, involving only about 100 scientists (projects
such as ATLAS have thousands). The goal is to measure how
particles scatter at small angles from
proton-proton collisions in the LHC. Collisions studied by
TOTEM include those where one proton or both protons survive the
crash, enabling scientists to calculate the likelihood of a
collision destroying both protons. Those numbers, in turn, tell
researchers the probability of producing particular particles in
a collision.

One thread connecting all experiments at the Large Hadron
Collider is the hope that something new and unexpected will
arise.

"There's certainly a long history in physics where you get the
ability to look at things at much smaller and smaller scales, you
see something you didn't expect," Woit told LiveScience. "They're
hoping the LHC would find something that we hadn't thought of.
And that hasn’t happened yet, and maybe it never will."